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Difference between revisions of "Location Based Scanning"

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== Overview ==
 
== Overview ==
  
Location-based scanning is a patented function of certain Uniden DMA scanners.
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Location-based scanning is a patented function of certain Uniden DMA scanners.  
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*RR Wiki: [[Uniden_DMA_FAQ]]
 
*RR Wiki: [[Uniden_Scanner_GPS_Features]]
 
*RR Wiki: [[Uniden_Scanner_GPS_Features]]
 
*Uniden TWiki: [http://info.uniden.com/twiki/bin/view/UnidenMan4/LocationBasedScanning Location Based Scanning]
 
*Uniden TWiki: [http://info.uniden.com/twiki/bin/view/UnidenMan4/LocationBasedScanning Location Based Scanning]

Revision as of 10:57, 20 October 2011

Overview

Location-based scanning is a patented function of certain Uniden DMA scanners.

According to Uniden, location-based scanning allows you to control which systems/sites and channel groups are scanned based on your exact location. This frees you from having to manually enable and disable systems or channel groups as you change location. Specifically, location-based scanning uses the scanners lockout function to control what is scanned based on your location. It unlocks systems, sites, or channel groups when you are inside an element's radius. When you exit the radius, the element is temporarily locked out.

Uniden scanners BCD996T, BCT15, BCT15X and all XT models (BC346XT, BCD396XT, BCD996XT) support user controlled location-based scanning. The term ‘user controlled’ refers to programming locations into the scanner. This can be done manually or imported from the Radio Reference database (RRDB) using a third party software.

The Uniden HomePatrol-1 (HP-1) also supports location-based scanning, but user control is somewhat limited to the HP-1 data. In addition to location based scanning, the HP-1 was designed for regional or Zip-Code based scanning.

Zip-Code based scanning is prevalent in scanners that come pre-loaded with the nationwide database. Users enter a Zip-Code, a range in miles, and the types of services they want to hear. Within seconds users can be listening to all Police Dispatch calls within a 5 miles range of downtown Indianapolis, etc.

The scanners do not have a GPS receiver built-in, you must purchase an aftermarket GPS device compatible with your scanner. Details for connecting a GPS receiver vary by scanner. The GPS devices described above all use the common DB9 serial type connection. For the mobile (996) scanners you can connect directly to the rear port of the scanner. For the portable scanners (346XT and 396XT) you can use the data cable that was supplied with the scanner. Some installations may require a gender changer to mate DB-9 connections. A ‘null modem adapter’ is required if using the data cable that came with the scanner. A null modem adapter is not required if you purchase the GPS cable adapter designed for use with the HP-1.

The GPS function of your scanner can be used for more than just controlling what you listen to. In addition to the basic GPS functions, for every entry you want to monitor with your scanner, you can program a set of criteria using GPS coordinates and a range. To better understand how this works, you should become familiar with how to program your scanner with third party software. You can program manually, but it can be more difficult and time consuming.

How it works with radio calls

In addition to knowing how to program your scanner and an understanding of programming locations (described above) you should have a general understanding of where RadioReference stores location data with its radio data that can be downloaded by third party software.

The RadioReference database is by no means complete, but it has the capability to store all of the info necessary for Location-based Scanning and Zip-Code based Scanning. You can cut and paste the info from the database for free, but to download this information directly into your scanner you will need a third party software that is capable of connecting to RadioReference and you will need a paid subscription to RadioRefernce.com website for access. Most of the DMA supported applications are Location-Based scanning capable.

(For HP-1 users, you do not access RadioReference directly. Uniden provides HP-1 owners with weekly updates for no charge via the Sentinel software. Uniden extracts data from RadioReference and tweaks it for the HP-1 radio.)

While it is not necessary to know the specific names of data fields, currently the RadioReference database stores location and zip code data in several database fields that are not used for Location-based scanning, such as: Zip-Code info and FCC location, etc. As use case example, when you review any agency info in the database if you click on the FCC license call sign the GPS coordinates registered with the FCC will sometimes be shown. This data is not what is used for location based scanning.

Most importantly you will simply want to understand the capabilities of the scanners and the fields that are used by the RadioReference Web Service to interface with third party software that connects to the database and extracts useable data.

The XT model scanners are capable of storing coordinates with each Trunked Radio Site within a system (this can be single site systems or milti-site systems) and within each set or “GROUP” of Talk Group ID’s (TGID) within a system. The XT models also can store coordinates for a set or “GROUP” of frequencies within a conventional system. The non-XT models handle coordinates differently and do not store GPS coordinates at the TGID level, you can only segment by trunk site. For the conventional entries on the non-XT models the GPS data is stored at the conventional system level, not the group level – which may or may not be the say depending on what you have programmed. In either cases data is retrieved from RadioReference the same for both scanner types. (For the Home Patrol, this is transparent to the user since it is translated to the Home Patrol database by Uniden on a weekly basis.)

Understanding GPS data in the RadioReference database

It is very helpful to be aware of the RadioReference database fields that match up to what can be used in the scanners. Each description below is followed by a link where RadioReference users can view the specific data online. The following fields correspond directly to the data used in the scanners.

Trunked System site – a trunking site can have specific location data assigned to it. If none is specified, then it inherits the location data based on the county that it is located in. If no county is defined for the site, the site inherits the trunked system default location data. The name of the field used by the third party software is called TrsSite

http://www.radioreference.com/apps/db/?rpt=7&sid=XXXX

Trunked System Talkgroup category – a talkgroup category can have specific location data assigned to it. If none is specified, it inherits the trunked system default location data. The name of the field used by the third party software is called TalkgroupCat

http://www.radioreference.com/apps/db/?rpt=8&sid=XXXX

Frequency Subcategory - a conventional frequency subcategory can have specific location data assigned to it. If no location data is specified for the frequency subcategory, then it inherits location data from the parent agency or county. The name of the field used by the third party software is called subcat

http://www.radioreference.com/apps/db/?rpt=6&ctid=XXXX

http://www.radioreference.com/apps/db/?action=locPop&scid=XXXX

RadioReference members can submit data for any of these fields where there is none or where there are errors. (Remember, if you are submitting data, that the coordinates and range should be entered for the intended useable area, not the coverage area. For example, if Agency XYZ has a 300 watt repeater that you can hear for miles away from the city, the intended usable area is more likely to be the agency boundary of the city or county. When submitting data to the database you would enter the radius necessary to cover the city or county, not a larger radius to cover the capable listening area of the transmitter.) Users who desire to add Location_Based_Info should become very familiar with RR_Database_Submission_Guidelines before submitting changes to the RadioReference database.

The descriptions of the fields described above make reference to ‘inheriting’ data from higher levels of the database. There are multiple fields that the RadioReference User cannot see by looking at the database online. The key fields relevant to location-based scanning that you cannot see are as follows:

  1. State – a state can have location data assigned to it that serves as a default set of location data for the state or for state agencies
  2. County – a county can have location data assigned to it that serves as a default set of location data for the county.
  3. Agency – an agency can have location data assigned to it that serves as a default set of location data for the agency.
  4. Trunk System – a trunked system can have location data assigned to it that serves as a default set of location data for the entire system.

The RadioReference database does not natively process or show the Internet user any inherited data. For example, if you were to review the online report for any conventional frequency subcategory data, if there is no data entered for that subcategory you will see absolutely no data. The ‘inherit’ feature is interpreted only by the third party software programs that are consumers of RadioReference data.

Using thrid party software with GPS features

It is important to make sure the software you have selected uses the ‘inherit’ feature capability if you expect to download accurate GPS data. Each time RadioReference changes the structure of its database they release a set of code or instructions to third party vendors so they can utilize any new features. The “inherit” capabilities were released in version 8 of the Radio Reference Web Service. The current release is version 9 and many third party software vendors are using release 9 or in the process of upgrading their programs to be compatible. If you are not sure, or you are downloading unexpected GPS data that doesn’t match what you expect or what is in the RadioReference database, ask the vendor of the software product you have selected.

Third party software using older versions of the Radio Reference Web Service can cause missing and/or erroneous location-based data to be downloaded. In addition, programs that are designed to program a variety of scanners may be misleading you as to where the data is being stored or used; it is possible that the program is downloading data in one location that would be used with XT models and data in another location that would be used with other models, etc. Without a good knowledge of the scanners and data explained above, any user could be easily confused.

Someday, ‘seamless’ GPS scanning may be a reality. For now, the data in the RadioReference database is only as good as what scanner enthusiasts populate into the database and the completeness of the database is evolving only as fast as users are adding data. To this accord, there may be cases where you want to enter your own data directly into the third party software before uploading to your scanner.

Most of the third party programs that handle location-based scanning have some sort of tools for viewing maps and searching locations necessary for programming locations. While the focus of this article has been how to understand the data that is downloaded from RadioReference automatically, there are some advantages to programming locations on your own.

Tips / Tricks for more effective location-based scanning

Not every city is the shape of a circle or is of moderate size. You may need to consider custom shapes and large listening areas when programming your scanner. As briefly suggested overview Wiki linked at the beginning of this page, you can create a duplicate site with a different radius to make an oblong entity. Essentially, the scanner narrows and expands the coverage area by scanning the same site twice (but it doesn’t slow the scan rotation enough to be noticeable to the end user since it only scans twice in overlap areas.) Your scanner also needs to be able to handle large geographical areas for statewide and nationwide channels in a scan rotation.

In the future, both the RadioReference database and some scanners will also have the option of using multiple rectangles to define areas for a single entry, but for now using duplicate entries with different radiuses is the only way to create your own custom shaped listening area. (The HP-1 already can use rectangles, but no support is available in RadioReference yet.) As location-based scanning popularity grows, the number of users submitting changes and updates to the database will increase and the data will become more robust and accurate.

  1. A custom shaped listening area can be as simple as an oblong shape or it can accommodate the rare instance you may monitor a system that operates in two simulcast locations separated by a long distance. As a complex example, imagine a large military simulcast system with more than one base or campus. Your main listening area is base A & B & C (or however many campus locations.) Instead of drawing a large radius around the 3 campus locations you could create multiple sites for each location and have a radius for each that only covers the specific campus. If the military police travel one or two miles down certain roads to get from point A to point B, you can create more sites with smaller radius that follow the roads, essentially giving you location-based scanning coverage of just the areas in which the military police operate, the 3 main campuses and the roads in between.
  2. Statewide systems, depending on your state, may need to have custom shapes defined. GPS data for states in the radio reference database are all based on a perfect circle surrounding an entire state. In rare cases for statewide agencies listed in the database the agency may inherit the statewide coordinates if there are no agency, county, or subcategory coordinates entered in the database. However, you must be aware that the XT model scanners are only capable of storing a radius of up to 125 miles and the other models are only capable of up to 50 miles radius. If you live in an average or larger size state, you will likely encounter this situation. The data stored in the RadioReference database may not be useable in your scanner and may not be processed correctly by your third party software. In this case you can duplicate entries with different radius information to cover a large area – similar to the tip / trick above for odd shape sites.
  3. Nationwide frequencies listed in the RR are now able to be downloaded into many third party software programs. All of the Nationwide frequencies have a center point in the middle of the US and a range of 1800 miles. While the scanners have limitations on the range of a frequency, site or system, it would be memory prohibitive to draw many circles and enter duplicate entries for any Nationwide channels. You can always tell the software not to scan a particular entry using GPS. You will want to set all Nationwide frequencies to scan all the time, and you can manually lock them out if you need to. They will be active wherever you go (which is how scanning used to work anyhow, remember?)

In the future, both the RadioReference database and some scanners will also have the option of using multiple rectangles to define areas for a single entry, but for now using duplicate entries with different radiuses is the only way to create your own custom shaped listening area. (The HP-1 already can use rectangles, but no support is available in RadioReference yet.) As location-based scanning popularity grows, the number of users submitting changes and updates to the database will increase and the data will become more robust and accurate.




Location-based scanning can be as simple or complex as you want it to be. If you live in a major metropolitan area you can detail most Uniden scanners for your listening enjoyment to precisely where you are at any given moment. If you travel cross country you can attach GPS to your Uniden Home Patrol and drive from coast to coast without reprogramming and without missing the local action along the way.